Road oil and method of preparing the same



the preferential wetting of road aggregates in the presence of water and has as a further object Patented May 28, 1935' I RoAn 0a mnmemonnemerhtme THE SAME I mempiric: j

Peter AlexandrofflLondon, England, assignor to Shell Development Company, San'Francis co,

Calif.

No Dra WingQH Application December l5 i13 2,

Serial No. 647,410; 22, 1 9s1- 1 This, invention relates to road oils a-nd has asits primary object to improve theadhesive properties of road oils, particularly in respectof their properties of resistance to moisture and to provideimproved road aggregates. I,

Various substances especially mineral oil :distillates or residues and also tar distillates or residues have already been proposed for the purpose of fiuxing' or cutting back asphaltic bitumens in order to improve the properties of the latter materials for use in road constructions. However, the road oils produced by the hitherto known methods have generallynot been entirely satisfactory inasmuch as they do not adhere readily to wet aggregates'and even if satisfactory adhesion is obtained the road oils may be entirely or partially removed from the aggregates by subsequent exposure to water. It has also been proposed to promote the adhesion of bitumen to road aggregates, especially if the latter are wet, by applying to the aggregate a priming coat of mineral oil distillate or tar distillate, prior to the application of the bitumen.

According to the invention it has been found that high boiling fractions obtained from tar distillates or residues and/ or distillates or residues resulting from the cracking of petroleum or the like either alone or incorporated with road oils possess in a marked degree the property of preferential wetting of road aggregates in the presence of water.

According to the invention. the method for' preparing materials having preferential properties for wetting road aggregates in the presence of water consists in separating high-boiling fractions from tar distillates or residues and/or distillates or residues of cracked petroleum or the like, such as by subjecting said distillates or residues to further distillation and, if desired, admixing the resulting products with road oils or other bituminous materials. The latter materials may thereupon be fiuxed or cut back by admixing a light mineral oil distillate, such as kerosene, so as to produce road oils of the desired viscosity, Alternatively the said; high-boiling fractions may be applied to the road aggregate as a priming coat, prior to the application of the bituminous binder. r

In an embodiment of the invention ordinary commercial creosote is further distilled and yields a viscous residue, which is practically odourless and possesses in a marked degree the property of preferential wetting of road aggregates in the In qreat Britain pecember 5 Claims. (01. 106 31) presence of water, that is to say when both water and the viscous residue from creosote are present the, various types of stone commonly used in road making are wetted by the creosoteresidue rather than by the .water. The said distillation has the effect of removing most of the phenolic and other substanceswhich impart to-thecreosote its particular coal tar smell whilst also being poisonous, :sothat; in many cases commercial creosote when applied on roads has been found to cause pollution of the bordering water-ways.

In another embodiment of the invention soft coal tar pitch is extracted with benzol and the benzol extract is subjected to distillation in order to separate the solvent. The residue thus obtained containing the benzol-soluble constituents of the soft coal tar pitch, on being used in the preparation of bituminous road oils, was found to impart to the said oil very good preferential wetting properties.

In a further embodiment of the invention, in order to impart the desired preferential wetting properties, use is made of distillates or residues resulting from the cracking of petroleum or the like, as it was found that cracking products in general show to a very marked degree the property of preferential wetting road aggregates, in contradistinction to corresponding mineral oil products obtained by ordinary distillation of the crude oils, the wetting capacity of which may in many cases be insuiiicient.

The following examples illustrate how the invention may be applied to improve road oils:

1. A standard B. E. S. A. (British Engineering Standards Association) specification creosote is distilled at atmospheric pressure to 270 C. (temperature of the vapour) The creosote yields 34% by weight of residue having a viscosity (Redwood I) at F. of 620 secs.

Six parts of this creosote residue are mixed with 94 parts by weight of asphaltic bitumen of 45 penetration and a material is produced having a penetration of 106 at 25 C. This material is then cut back with a peteroleum distillate to a viscosity (Redwood II) at 100 F. of 1740 secs.

It should be understood that the quantity of the residue and/or its viscosity and the temperature of distillation will vary according to the nature of the creosote employed.

2. 5 per cent of the benzol-soluble constituents of soft coal tar pitch after separation of the ben- 201 are added to an ordinary road oil consisting of petroleum products.

3. A very satisfactory road oil was prepared by fluxing an oil distillation bitumen of penetration -100 with a Mexican cracked kerosene having a boiling point range of about -250 C., a flash point of about 39 C. and a bromine number of about 32, in the proportion of about 83 parts by weight of bitumen and 17 parts by weight of cracked kerosene.

When preparing under equal conditions a road oil with the same bitumen fluxed with a straightrun kerosene having substantially the same boil- 7 ing point range and flash point and a low bromine number, the resulting road oil was found to possess but an inferior preferential wetting capacity. 3

Instead of cracked kerosene use may be made also of pressure distillate bottoms or similar cracking products as fluxing agents.

The road oils prepared in accordance with this invention may be used in any known process of road constructions in the manner as usual for road oils of the same general character.

What I claim is: I

1. A road oil having the property of preferential wetting of road aggregates in the presence of water, comprising a mixture of undeteriorated asphaltic bitumen and a relatively small quantity of material selected from the group: a highboiling viscous substantially odorless residue from the distillation of creosote, benzol-soluble constituents of coal tar pitch, and-a high-boiling cracked petroleum distillate.

2. A road oil having the property of preferential wetting of road aggregates in the presence of water, comprising a mixture of undeteriorated asphaltic bitumen and a relatively small quantity of cresote residue boiling at temperatures above 3. A road oil having the property of preferential wetting of road aggregates in the presence of water, comprising a mixture of asphaltic bitumen andmai relatively small quantity of cracked petroleum distillate boiling at temperatures above 150 C.

4. A roadroil having the property of preferential wetting of road aggregates in the presence of water, comprising a mixture of asphaltic bitumen and a relatively small quantity of benzol- PETER ALEXANDROFF. 

